6 



BULLETIN 740, U. S. DEPARTMENT. *0F AGRICULTURE. 



no appreciable amount takes place while the oysters are stored in 

 the refrigerating room of the oysterhouse for a short time. It is 

 interesting to note that the figure for the larger oysters, selects and 

 counts, is uniformly smaller than that for the standards of the same 

 stock. 



From the results obtained in this series, there appears to be no 

 relation between the amino-acid nitrogen and the ammoniacal 

 nitrogen present. In general, the figures for ammoniacal nitrogen 

 change in the same way as do those for amino-acid nitrogen ; but the 

 former are so inconsistent, even in duplicates run on the same sample, 

 that the whole table is practically meaningless in this connection. 

 Similar determinations were run in all the following series of experi- 

 ments, but as they are in all cases as conflicting as those in Tables 1 

 and 2, they have been omitted from all subsequent tables. 



SERIES II. 



In order to prove that the amount of amino-acid nitrogen and 

 ammonia present would not indicate decomposition in oysters if the 

 water over them was changed occasionally, the following series of 

 experiments was run. 



A 5-gallon can of oysters was divided into two lots, and the oysters 

 in each were covered with water. One lot was stored at room temper- 

 ature, the other in a small ice box at a temperature of about 45° F., 

 and the water over each lot was changed every day. Determina- 

 tions were run upon each lot every day for one week. A summary 

 of results obtained is given in Table 2. 



Table 2. — Amino-acid and ammoniacal nitrogen as index of decomposition. 



Date of analvsis. 



Amino-acid nitrogen 

 in portion stored at— 



Ammoniacal nitrogen 

 in portion stored at— 





Room temp. 



45° F. 



Room temp. 



45° F. 



1914. 

 Oct. 5 



Per cent. 

 0.1290 

 .1250 

 .1244 

 .1075 

 .1250 

 .1250 

 .1215 



Per cent. 

 0.1290 

 .1250 

 .1272 

 .1120 

 .0687 

 .0676 

 .0638 



Per cent. 

 0. 00123 

 .00116 

 .00329 

 .00165 

 .00392 

 .00185 

 .00473 



Per cent. 

 0.00123 



Oct. 6 



.00116 

 .00259 



Oct. 8. 





Oct. 9 



.000105 



Oct. 10 



.000098 

 .000840 







At the end of this time the oysters soaking at room temperature 

 were badly decomposed. In spite of this condition, the ammo-acid 

 nitrogen content decreased, and the figure for ammoniacal nitrogen, 

 though larger than in the same oysters at the beginning of the experi- 

 ment, was smaller than that found in several samples of fresh oysters. 

 The oysters stored in the refrigerator kept much better than those 

 stored at room temperature, though they also were slightly decom- 



